US20130168035A1

US20130168035A1 - Method and system for manufacturing railcar coupler locks

Info

Publication number: US20130168035A1
Application number: US13/338,998
Authority: US
Inventors: F. Andrew Nibouar; Jerry R. Smerecky; Kelly S. Day; Nick Salamasick
Original assignee: Bedloe Industries LLC
Current assignee: Bedloe Industries LLC
Priority date: 2011-12-28
Filing date: 2011-12-28
Publication date: 2013-07-04
Also published as: CZ20131080A3; CA2840841C; RU2013158935A; AU2012362441A1; BR112013033978A2; WO2013101876A1; CA2840841A1; MX2014000252A; CN103492101A

Abstract

A casting assembly for manufacturing a lock of a railcar coupler includes drag and cope portions of a first mold that defines exterior surfaces of the lock, wherein the first mold comprises a first molding material. The casting assembly also includes a second mold formed of a second molding material. The second mold defines a cavity with an interior surface that substantially complements an exterior surface of the first mold. A down sprue is formed in the second mold. A gating system is formed in the second mold that and is in fluid communication with the down sprue. An in-gate is formed in the second mold and is in fluid communication with the gating system and the first mold.

Description

BACKGROUND

Railway car couplers are used to couple railway cars together. A typical coupler used throughout North America is the Type-E or Type-F coupler. These couplers incorporate a lock that interacts with a knuckle of the coupler to lock the knuckle into a closed position. Generally, the lock fits within a lock chamber of the knuckle body and over a knuckle tail. The width of the lock is sized to slide within the lock chamber.
Locks used in such couplers are typically formed via a casting process. The most common technique for producing a lock is through sand casting. Sand casting offers a low cost, high production method for forming complex shapes. In a typical sand casting operation, a mold is formed by packing bonded sand around a pattern, which generally defines a gating system through which molten metal flows. The pattern is then removed from the mold forming the cavity in the shape of the part being cast, which corresponds to the final cast part. Cores for defining internal cavities and slots are placed into the mold. The mold is then closed and filled with hot liquid metal through a down sprue and the metal is allowed to cool in the mold. The solidified metal or raw casting is removed by breaking away the mold. The casting is then separated from the gating, finished, and cleaned via grinding, welding, heat treatment, and machining.
In a sand casting operation, the mold is created using sand as a base material, mixed with a binder to retain the shape. The mold is created in two portions referred to as a cope portion (i.e., top half) and drag portion (i.e., bottom half), which are separated along a straight parting line. Draft angles of up to 3 degrees or more are machined into the pattern to ensure the pattern releases from the mold during extraction. In some sand casting operations, an exterior flask is used to support the sand during the molding process through the pouring process.
After the metal has been poured into the mold, the casting cools and shrinks as it approaches a solid state. As the metal shrinks, additional liquid metal must continue to feed the areas that contract, or voids will be present in the final part. In areas of high contraction, risers are formed in the mold to provide a secondary reservoir, available during filling. These risers are the last areas to solidify, and thereby allow the contents to remain in the liquid state longer than the cavity of the part being cast. As the contents of the cavity cool, the risers feed the areas of contraction, ensuring a solid final casting is produced. Risers that are open on the top of the cope mold can also act as vents for gases to escape during pouring and cooling.
In the various casting techniques, different sand binders are used to allow the sand to retain the pattern shape. These binders have a large effect on the final product, as they control the dimensional stability, surface finish, and casting detail achievable in each specific process. The two most typical sand casting methods include (1) green sand, consisting of silica sand, with clay and water as a binder; and (2) chemical or resin binder material consisting of silica sand and fast curing chemical binding systems such as phenolic urethane. Traditionally, locks have been created using the green sand process, due to the lower cost associated with the molding materials.
While the green sand has been effective at producing locks for many years, there are disadvantages to this process. For example, the surface finish of the locks tends to be rough and the thickness over the locking surfaces from lock to lock may vary. These rough surface defects and variations must be removed via grinding and other finishing operations to ensure that the final lock meets required dimensional requirements. Other problems with these casting operations will become apparent upon reading the description below.

BRIEF SUMMARY

An object of the invention is to provide a method of manufacturing a lock of a railcar coupler that substantially eliminates surface defects and dimensional variations. The method includes forming a pattern of a lock in drag and cope portions of a first mold that comprises a first molding material to thereby form a cavity that defines exterior surfaces of the lock. A cavity is formed in a second mold that comprises a second molding material. The cavity defines an interior surface that substantially complements an exterior surface of the first mold. A down sprue, gating system in fluid communicating with the down sprue, riser in fluid communicating with the gating system, and an in-gate in fluid communication with the gating system and the first mold, are formed in the second mold. The first mold and the second mold are cured. The first mold is assembled and inserted into the into the cope portion of the second mold. The second mold is assembled, and molten material is poured into the down sprue of the second mold. The molten material subsequently flows into the first mold to thereby form the lock.
A second object of the invention is to provide a method of manufacturing a lock of a railcar coupler that includes forming a pattern of a lock in drag and cope portions of a first mold that comprises a first molding material to thereby form a cavity that defines exterior surfaces of the lock. The cope portion defines a first opening configured to vent gases. A cavity with an interior surface that substantially complements an exterior surface of the first mold is formed in a second mold that comprises a second molding material. A first opening configured to vent the gases vented from the first opening in the cope portion of the first mold is formed in the cope portion of the second mold. A down sprue, gating system in fluid communication with the down sprue, and an in-gate in fluid communication with the gating system and the first mold are formed in the second molding material. The first mold and the second mold are cured. The first mold is assembled and inserted into the into the cope portion of the second mold. The second mold is assembled, and molten material is poured into the down sprue of the second mold. The molten material subsequently flows into the first mold to thereby form the lock. Gases in the first mold are forced out by the molten material through the first opening in the cope portion of the first mold and subsequently through the first opening in the cope portion of the second mold.
A third object of the invention is to provide a method of manufacturing a lock of a railcar coupler that includes forming patterns for at least two locks in drag and cope portions of a mold that comprises an air-set molding material to thereby form cavities that define exterior surfaces of the at least two locks. A down sprue, gating system in fluid communication with the down sprue, and at least two in-gates, each in fluid communication with the gating system and one of the at least two cavities, are formed in the air-set molding material. The air-set molding material is cured. The drag and cope portions of the mold are assembled. Molten material is poured into the down sprue of the cured air-set molding material, wherein the molten material subsequently flows through the gating system and into the cavities to thereby form the at least two locks.
A fourth object of the invention is to provide a casting assembly for manufacturing a lock of a railcar coupler. The casting assembly includes drag and cope portions of a first mold that defines exterior surfaces of the lock. The first mold comprises a first molding material. The casting assembly also includes a second mold formed of a second molding material. The second mold defines a cavity with an interior surface that substantially complements an exterior surface of the first mold. A down sprue is formed in the second mold. A gating system is formed in the second mold and is in fluid communication with the down sprue. An in-gate is formed in the second mold and is in fluid communication with the gating system and the first mold.
Other features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional features and advantages included within this description be within the scope of the claims, and be protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the claims, are incorporated in, and constitute a part of this specification. The detailed description and illustrated embodiments described serve to explain the principles defined by the claims.

FIG. 1 illustrates a perspective view of a lock within the body of a railcar coupler;

FIGS. 2A and 2B illustrate perspective and side views, respectively, of the lock illustrated in FIG. 1;

FIG. 3 illustrates an outer mold assembly that may be utilized to form the lock of FIGS. 2A and 2B;

FIGS. 4A and 4B illustrate the interior of the cope portion and drag portion, respectively, of the outer mold illustrated in FIG. 3;

FIG. 5 illustrates an interior view of the outer mold after the molten material has been poured;

FIG. 6A illustrates a side view of a shell mold;

FIG. 6B illustrates the cope portion and drag portion of the shell mold illustrated in FIG. 6A;

FIG. 7A illustrates another view of the drag portion of the shell mold;

FIG. 7B illustrates a cross-section of the drag portion taken along section A-A′ of FIG. 7B;

FIG. 8 illustrates a drag portion cavity in relation to a cast lock; and

FIG. 9 illustrates operations for manufacturing the lock of FIG. 2A.

DETAILED DESCRIPTION OF THE DRAWINGS

The embodiments below describe a method for manufacturing a plurality of locks in a single casting operation. Generally, a group of shell molds that define the shape of the lock are formed. The shell molds are molds formed from relatively expensive fine silica sand that is mixed with a thermosetting phenolic resin. The fine silica results in a lock having a smooth surface finish and a relatively high degree of dimensional accuracy as compared to locks manufactured via other casting processes.
However, current shell mold production techniques are optimized for present size shell molding machines and result in shell molds that are relatively small. While larger shell molding machines exist, they tend to be prohibitively expensive. Increasing the size of the shell molds to withstand the required large head pressure, while technically possible, would be prohibitively expensive. Thus, the shell molds are placed into an outer mold. The outer mold is made from a lower cost air-set or pep set molding material and is configured to receive the shell molds. In the described embodiments, the outer mold is configured to receive four shell molds.
A gating system formed in the outer mold is configured to distribute molten material poured into the mold via a down sprue to each of the shell molds. Vent openings in the shell molds allow air and other gases to escape as the molten material fills the shell molds. The vent openings are generally aligned with vent openings in the outer mold to allow the gases to vent to the atmosphere.
FIG. 1 illustrates a perspective view of a lock 105 within the body 100 of a railcar coupler. FIGS. 2A and 2B illustrate perspective and side views, respectively, of the lock 105 illustrated in FIG. 1. The lock 105 includes a rear guide end 205, a leg portion 210 in a middle section, and a knuckle side end 215. The knuckle side end 215 defines a slot 220. Near the rear guide end 205, the lock 105 defines a knuckle locking surface 225 and a coupler locking surface 230.
Operation of the lock 105 requires that the lock 105 slide within the lock chamber of the knuckle body and over the knuckle tail. To facilitate smooth operation of the lock 105, the knuckle-locking surface 225 and coupler locking surface 230 must be substantially parallel to one another and smooth. In addition, the distance D 207 between the two surfaces needs to be accurate and consistent from lock to lock. The distance D 207 of locks 105 formed by the disclosed casting operations is about 3.060 inches and varies from lock-to-lock by less than about ±0.010 inches. These dimensions may be achieved via the claimed casting operations alone with minimal machining of the lock. Locks produced via known manufacturing processes must be finished to produce a smooth surface finish by sand blasting or other methods. Relatively thin vent castings may be hammered off leaving relatively small areas to be ground. Likewise, a casting connection 505 (FIG. 5) that connects the lock 105 at a side surface 207 of the rear guide end 205 to a gating system of the casting may be broken off. In some instances, the residual casting of the connection 505 may not require further grinding, as the side surface 207 is generally not a critical surface.
FIG. 3 illustrates a closed outer mold assembly 300 that may be utilized to form the lock 105 described above. The outer mold 300 includes a cope portion 305 and a drag portion 307. The cope and drag portions 305 and 307 are formed from a molding material, such as no-bake or air-set sand. Positioned within an opening of the cope is a down sprue 320 through which molten material is poured. The cope portion 305 defines a first and a second group of vent openings 325 and 330 for venting gases generated from within cavities formed in the outer mold 300 and by the outer mold 300 during the casting process. Vent openings 335 may also be provided in a side of the drag portion 307.
The molding material used in the outer mold 300 is a relatively low cost and strong molding material that is generally not capable of forming locks with the required detail of surface finish and dimensional accuracy. For example, the grain fineness number (GFN) of the molding material may be in the range of 44-55 GFN.
In some implementations, the molding material is reclaimed sand. (I.e., sand that has been previously used to make castings). The reclaimed sand may be obtained by subjecting used molds to various shaking and/or crushing operations that break down the mold classify the sand into finer and finer constituent sizes until a desired grain size is obtained. Screening operations facilitate separation of the sand by size. Finally, the sand is subjected to high temperatures to burn off any residual coating or other impurities, such as the binder material. The reclaimed sand is then mixed with new binder at a ratio of about 99:1 and placed into a mold and allowed to set. Once set, the new mold is ready to receive a molten material.
In some implementations, two or more grades of molding material may be used to form the outer mold 300. For example, an outer layer 310 of the mold (i.e., that defines the exterior of the outer mold may be formed from less refined sand. The less refined material may not be subjected to the various separation operations described above. For example, thermal operations may not be carried out to save time. Moreover, a lesser amount of binder material may be utilized to bind the less refined material. For example, the ratio of sand to binder may be greater than 99:1.
An inner layer 315 of the mold may be formed from the more refined sand reclaimed via the separation processes described above. Utilizing the different grades of reclaimed material reduces overall manufacturing costs associated with the outer mold 300 as less refined sand is required. The more-refined sand may be reserved for just those portions of the outer mold 300 that require greater dimensional accuracy, or better surface finish.
FIGS. 4A and 4B illustrate the interior of the cope portion 305 and drag portion 307, respectively, of the outer mold 300. In FIG. 4B, also shows the shell molds 400 positioned within the drag portion 307. The outer mold 300 is configured to receive four shell molds 400. The interior surface of the outer mold 300 that contacts the shell molds 400 is configured to provide a snug fit with the shell molds 400 so as to prevent the walls of the shell molds 400 from blowing-out under the head pressure generated when pouring molten material into the mold 300.
Each shell mold 400 is configured to form a single lock 105. Thus, four locks 105 may be formed in a single casting operation. It should be understood that the size of the outer mold 300 may be sized differently to accommodate a different number of shell molds 400 to facilitate casting a different number of locks 105 in a given casting operation.
In the illustrated embodiment, four sets of vent openings 325 and 330 are provided on the cope portion 305 of the mold to vent gases from the four shell molds 400. The vent openings 325 and 330 are generally positioned above respective vent openings 405 and 410 of the shell mold 400. A first group of vent openings 330 is positioned over a first group of vent openings 410 of the shell mold 400 near a position of the shell mold 400 that corresponds to a first end of the lock. (E.g., The rear guide end 205). A second vent opening 325 is positioned over a second vent opening 405 of the shell mold 400 in a position of the shell mold 400 that corresponds to a second end of the lock. (E.g., The knuckle side end 215). Side vents positioned adjacent to corresponding side vents 335 (FIG. 3) formed in the shell molds 400 are formed in the drag portion 307 of the outer mold 307.
The vent openings 330 and 325 in the outer mold cope portion 305 extend from the outside surface of the cope portion 305 (See FIG. 3) to the interior surface of the cope portion 305 (See FIG. 4A). Alignment of the respective vent openings 330, 325, 405, and 410 is critical to facilitate proper removal of gas generated during casting operations. The vent openings 325 and 330 of the outer mold cope portion 305 may be positioned within recesses 422 to relax the positioning constraints of the vent openings 330, 325, 405, and 410. The recesses 422 are sized to ensure that gas vented through the vent openings 405 and 410 of the shell mold 400 and other gases are captured within the recesses 422. That is, the recess 422 are sized to accommodate any variability in the relative positioning between the vent openings 325 and 330 of the outer mold cope portion 305 and the vent openings 405 and 410 of the shell mold 405. For example, the recesses 422 may have a width and length of about 1 in by 2 in. The depth of the recesses 422 may be about 0.125 in. It should be understood that the recesses could also be formed on the shell mold 400 to provide the same advantages.
Positioning of the vents 405 and 410 at either end of the lock 105 helps to ensure that any gas within the shell mold 400 has an escape path. This results in a stronger lock 105 with fewer surface defects because the gases, which could otherwise form air pockets that might weaken the lock 105, do not penetrate into the casting. The position of the vents 405 and 410 also helps ensure that the thick upper section of the lock 105 (i.e., the rear guide end 205) and thinner bottom section of the lock 105 (i.e., the knuckle side end 215) remain stable without distortion or dimensional changes given the significant difference in volumes of these two lock sections.
As illustrated in FIG. 4A, a pair of risers 415 is patterned in the cope portion 305 of the outer mold 300 and a gating system 420 is patterned in the drag portion 307 of the outer mold 300. During casting, molten material flows into the outer mold 300 through the down sprue 320, through the gating system 420, into the risers 415, and finally into the shell molds 400 via an in-gate 505 (FIG. 5) that connects the shells 400 to the gating system 420. As noted earlier, the risers 415 are cavities that fill with molten material during the pouring process. As molten material in other parts of the casting cools, molten material will be drawn into the casting from the risers 415. This in turn helps to prevent cracks from developing in those areas of the casting that cool more slowly than other areas of the casting.
FIG. 5 illustrates an interior view of the outer mold 300 after the molten material has been poured and solidified to form the casting. In the exemplary embodiment, the casting includes four locks 105, in-gates 505, the gating system 420, risers 415, and the down sprue 320. The in-gates 505 to the individual locks are sized to facilitate separation of the locks 105 from the casting via hammering or other form of impact. In this regard, the diameter of the in-gates 505 may be between about ½ inch and 2 inches. To minimize finishing of the lock 105 after separation, the in-gates 505 are advantageously positioned to feed the side 207 (FIG. 2A) of the rear guide end 205, which is a less critical region of the lock 105. After breaking off the locks 105, the remaining portions of the casting (i.e., the gating system, risers, and down sprue) may be melted down and used in subsequent casting operations.
FIG. 6A illustrates a side view of a shell mold 400 that may correspond to the shell molds 400 described above. FIG. 6B illustrates the cope portion 605 and drag portion 610 of the shell mold 400. The cope portion 605 and drag portion 610 may be joined via an adhesive to form the shell mold 400. For example, adhesives may be utilized to adhere the respective portions together.
The shell mold 400 is formed via a so called shell (thus the term shell mold) or hot box process whereby resin bonded sand or a sand/resin mix is blown via air pressure into heated metal pattern for a period of time to form a hardened shell. The sand may correspond to fine silica sand that is mixed with a thermosetting phenolic resin. For example, the silica may have a grain fineness number in the range of 60-70 GFN. The pattern may be formed from cast iron and then heated to between 230° C. to 315° C. until the sand in the pattern hardens to a suitable depth. That is, until the shell has the desired wall thickness. The shell may then be removed from the pattern and the bulk of the unhardened sand mixture inside the shell removed. The removed sand may be used for subsequent shell casting operations after a reclamation process.
The cope portion 605 and drag portion 610 of the shell mold 400 are formed via different patterns. The shell molding technique offers high dimensional stability. Each pattern defines a part of a connection opening 607 in the respective portion through which molten material flows into the shell mold 400. The pattern that defines the cope portion 605 may correspond to a generally rectangular box with an open side into which the sand is poured. The box may have tapered sidewalls that facilitate removal of the hardened cope portion 605 from the box. The cope portion of the lock 105 may be patterned in the bottom side of the box. In addition, the pattern may be configured to form a protrusion 620 in the cope portion 605. The protrusion 620 forms the slot 220 (FIG. 2A) in the lock. In other words, the slot 220 is formed without the use of cores, which typically move somewhat during casting. Thus, the dimensional accuracy of the slot 220 is improved as compared to slots formed with loose cores. This in turn eliminates finishing operations that are required to form slots produced via known casting operations, which reduces costs.
The pattern that defines the drag portion 610 may correspond to a generally closed box with a relatively small opening formed in a side. In an exemplary embodiment, the opening is formed on a side of the box that defines the knuckle side end 215 of the lock 105. Sand is blown into the box via the opening and hardened as described above. Uncured sand is removed via the small opening, leaving a venting cavity 710 (FIG. 7B).
FIG. 7A illustrates the drag portion 610 after being removed from the pattern. A residual buildup of sand 705 may be formed on the side of the drag portion 605 nearest the knuckle side end 215 as a result of the shell mold casting process. Excess unhardened sand is emptied from the drag portion 610 via the opening 335 formed inside the buildup 705. The opening 335 in the side of the drag portion corresponds to the opening 335 in the side of the outer mold 300, illustrated in FIG. 3. Removal of the excess sand exposes a venting cavity 710 in the drag portion 605, as illustrated by cross-section A-A′ 712 of the drag portion 605 shown in FIG. 7B.
As illustrated in FIG. 8, the pattern for the drag portion 605 of the shell mold 400 is configured so that the venting cavity 710 (dashed line) substantially follows the shape of the leg portion 210 of the lock 105. That is, the venting cavity 710 follows a substantial portion of the lock 105. This enables gases formed during casting to escape into the venting cavity 710 and out through the vent opening 335 rather than into the cast part, which as noted above, would otherwise result in additional air bubbles in the cast part that would weaken the part, or result in surface defects that would have to be repaired. This form of venting further improves the dimensional accuracy of the lock 105.
Returning to FIG. 6A, a parting line 615 that separates the cope portion 605 from the drag portion 610 forms a non-linear path that follows the natural draft of the contour of the lock 105 as it proceeds from the rear guide end 205 section down through the leg portion 210 and to the knuckle side end 215. The non-linear path facilitates self-alignment of the cope and drag portions 605 and 610 of the shell mold 400 and results in a parting line 615 of the lock 105 that generally follows the non-linear contour of the lock 105.
FIG. 9 is a block diagram of operations that may be performed in forming the lock 105 described above. At block 900, cope and drag portions 605 and 610 of a shell mold 400 for casting the lock 105 may be formed. The respective portions may be formed from fine silica sand that is covered in a thin coating of thermosetting phenolic resin. The sand is inserted into respective boxes that define cope and drag patterns and heated until a shell with a desired thickness is obtained. Excess sand is removed from the drag portion 610 of the shell mold 400 to expose a venting cavity 710 that facilitates venting of gases from the drag portion 610 during casting. The cope and drag portions 605 and 610 are attached to one another via an adhesive. A non-linear parting line 615 that separates the cope and drag portions 605 and 610 facilitates easy alignment of the respective portions.
At block 905, cope and drag portions 305 and 307 of an outer mold 300 are formed. The cope and drag portions 305 and 307 are formed from relatively inexpensive materials such as an air-set or pep-set material. Reclaimed material from previous casting operations may be utilized for part of the outer mold 300. The interior of the outer mold 300 is patterned to receive the shell molds 400 and to provide a tight fit with the shell molds 400 so as to support the walls of the shell mold 400 during casting.
A gating system 420 and one or more risers 415 may be patterned in the interior of the outer mold 300. The gating system 420 connects to respective shell molds 400 via an in-gate 505. The in-gate 505 is sized to facilitate separation of the lock 105 from the casting via hammering or other form of impact.
At block 910, the shell molds 400 are inserted into the outer mold 300. At block 912, the outer mold is assembled. Then, at block 915 molten material is poured into a down sprue 320 of the outer mold 300. The molten material may be steel or other suitable material. The molten material flows down through the down sprue 320, through the gating system 420, and into the shell molds 400 via the connections 505. Air and other gases that would otherwise be trapped in the shell mold 400 escape through vent openings 405 and 410 defined in the cope portion 605 of the shell mold 400 and subsequently through vent openings 325 and 330 defined in the cope portion 305 of the outer mold 300. The vent openings 325 and 330 in the outer mold 300 are generally positioned over the vent openings 405 and 410 of the shell mold 400. Other gases escape from the shell mold 400 via the cavity formed in the drag portion 605 of the shell mold 400. These gases exit via an opening 335 in the side of the drag portion 605 of the shell mold 400 and finally vent to the atmosphere via an opening in the side of the outer mold 300.
At block 920, the hardened casting is removed from the mold 300. For example, the mold 300 may be broken apart to expose the casting. The spent mold sand may be broken down and reclaimed to form subsequent molds.
At block 925, the locks 105 are separated from the casting. For example, an impact hammer may be used to break the gating system 420 and the connection 505 off the locks 105.
At block 930, the locks 105 are finished. For example, the side 207 of the lock 105 to which the connection 505 was formed may be ground to a relatively smooth finish. Any remaining material of the gating system may be ground off. The remainder of the lock 105 may then be sand blasted to a smooth surface finish. After sand blasting, the lock 105 may be ready for operational use. That is, the lock 105 may be ready to be inserted into a coupler body 100 without the need for further finishing.
As described, the exemplary embodiment for forming the lock facilitates the manufacture of a lock 105 requiring minimal finishing. For example, a shell mold 400 made of fine silica is utilized to define the lock casting. The shell mold is supported by a relatively inexpensive outer mold formed from and air-set or pep-set material. Multiple locks are capable of being produced by accommodating multiple shell molds within the outer mold. A gating system and risers are formed in the outer mold to distribute molten material to the respective shell molds. Vents formed in the respective molds allow gases to escape thus improving the dimensional accuracy to the lock.
While various embodiments of the embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the claims. The various dimensions described above are merely exemplary and may be changed as necessary. Accordingly, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the claims. Therefore, the embodiments described are only provided to aid in understanding the claims and do not limit the scope of the claims.

Claims

We claim:

1. A method of manufacturing a lock of a railcar coupler, where the lock includes a rear guide portion at a first end, a leg portion in a middle section, and a slot at a second end, where a knuckle side surface of the lock near the first end defines a knuckle locking face and a coupler side surface of the lock that is opposite to the knuckle side surface defines a coupler locking face, the method comprising the steps of:

forming a pattern of a lock in drag and cope portions of a first mold that comprises a first molding material to thereby form a cavity that defines exterior surfaces of the lock;

forming, in a second mold that comprises a second molding material, a cavity with an interior surface that substantially complements an exterior surface of the first mold;

forming, in the second mold, a down sprue, a gating system in fluid communication with the down sprue, a riser in fluid communication with the gating system, and an in-gate in fluid communication with the gating system and the first mold;

curing t he first mold and the second mold;

assembling the drag and cope portions of the first mold;

inserting the first mold into the second mold;

assembling the drag and cope portions of the second mold; and

pouring a molten material into the down sprue of the second mold, wherein the molten material subsequently flows into the first mold to thereby form the lock.

2. The method according to claim 1, further comprising inserting the first mold into the cavity of the second mold.

3. The method according to claim 1, wherein the first mold is a shell mold that includes an in-gate, and wherein during formation of the first mold uncured first molding material is removed from the first mold via a vent opening defined in a side of at least one of the drag and cope portions of the first mold to thereby reveal a venting cavity in the at least one portion, wherein the venting cavity is not connected to the cavity that defines the exterior surfaces of the lock.

4. The method according to claim 1, wherein outside walls of the first mold are tapered.

5. The method according to claim 1, wherein a parting line of the first mold that separates the cope portion from the drag portion follows a non-linear contour of the lock.

6. The method according to claim 1, wherein the first molding material is a mixture of silica sand and a thermosetting phenolic resin.

7. The method according to claim 6, wherein the second molding material is an air-set material.

8. The method according to claim 7, wherein the second molding material comprises a first layer of mechanically separated sand that forms an outer portion of the mold, and a second layer of mechanically and thermally separated sand that forms an interior of the second mold that comes in contact with the first mold.

9. The method according to claim 1, wherein the first molding material and the second molding material are a same material.

10. The method according to claim 1, wherein immediately subsequent to removal of the lock from the first mold, a tolerance of a distance between the resulting knuckle locking face and the resulting coupler locking face of the resulting lock is less than or equal to about ±0.010 inches.

11. The method according to claim 1, wherein at least one of the cope portion and the drag portion of the first mold defines a protrusion that forms the slot.

12. The method according to claim 1, wherein the interior of the drag portion of the second mold is configured to receive at least two shell molds and to distribute the molten material to each of the at least two shell molds.

13. The method according to claim 1, wherein the in-gate to the lock that is formed during casting is configured to be broken off.

14. The method according to claim 13, wherein a diameter of the in-gate is less than 2 inches.

15. The method according to claim 13, wherein the in-gate to the lock is located on a top of the first end of the lock.

16. A method of manufacturing a lock of a railcar coupler, where the lock includes a rear guide portion at a first end, a leg portion in a middle section, and a slot at a second end, where a knuckle side surface of the lock near the first end defines a knuckle locking face and a coupler side surface of the lock that is opposite to the knuckle side surface defines a coupler locking face, the method comprising the steps of:

forming a pattern of a lock in drag and cope portions of a first mold that comprises a first molding material to thereby form a cavity that defines exterior surfaces of the lock, wherein the cope portion defines a first opening configured to vent gases;

forming, in the cope portion of the second mold, a first opening configured to vent the gases vented from the first opening in the cope portion of the first mold;

forming, in the second mold, a down sprue, a gating system in fluid communicating with the down sprue, and an in-gate in fluid communication with the gating system and the first mold;

curing the first mold and the second mold;

assembling the drag and cope portions of the first mold;

inserting the first mold into the second mold;

assembling the drag and cope portions of the second mold; and

pouring a molten material into the down sprue of the second mold, wherein the molten material subsequently flows into the first mold, via the gating system and in-gate, to thereby form the lock, wherein gases in the first mold are forced out by the molten material through the first opening in the cope portion of the first mold and subsequently through the first opening in the cope portion of the second mold.

17. The method according to claim 16, wherein the cope portion of the first mold defines a second opening configured to vent gas, wherein the first opening in the cope portion of the first mold is positioned in proximity to the first end of the lock and the second opening in the cope portion of the first mold is positioned in proximity to the second end of the lock.

18. The method according to claim 17, wherein the first opening is positioned at a location of the lock that is closest to a top surface of the cope portion of the drag mold.

19. The method according to claim 16, wherein the cope portion of the second mold defines a second opening configured to vent the gases vented from the second opening in the cope portion of the first mold.

20. The method according to claim 16, wherein the cope portion of the second mold defines a recess around the first opening in the cope portion of the second mold, and a width of the recess is about 1 in and a length of the recess is about 2 in.

21. The method according to claim 20, wherein a depth of the recess is greater than about 0.125 in.

22. The method according to claim 16, wherein the cope portion of the first mold defines a venting cavity positioned substantially adjacent to a region of the cope portion that forms the leg portion of the lock, wherein the venting cavity does not receive molten material during casting and is configured to vent gas via an opening formed in a side of the cope portion of the first mold out through a side opening formed in the second mold.

23. The method according to claim 16, wherein immediately subsequent to removal of the lock from the first mold, a tolerance of a distance between the upper locking face and the lower locking face of the lock is less than or equal to about ±0.020 inches.

24. A method of manufacturing a lock of a railcar coupler, where the lock includes a rear guide portion at a first end, a leg portion in a middle section, and a knuckle side that defines a slot at a second end, where a knuckle side surface of the lock near the first end defines a knuckle locking face and a coupler side surface of the lock that is opposite to the knuckle side surface defines a coupler locking face, the method comprising the steps of:

forming patterns for at least two locks in drag and cope portions of a mold that comprises an air-set molding material to thereby form cavities that define exterior surfaces of the at least two locks;

forming, in the air-set molding material, a down sprue, a gating system in fluid communication with the down sprue, and at least two in-gates, each in fluid communication with the gating system and one of the at least two cavities;

curing the air-set molding material;

assembling the drag and cope portions of the mold; and

pouring the molten material into the down sprue of the cured air-set molding material, wherein the molten material subsequently flows through the gating system and into the cavities to thereby form the at least two locks.

25. A casting assembly for manufacturing a lock of a railcar coupler, where the lock includes a rear guide portion at a first end, a leg portion in a middle section, and a slot at a second end, where a knuckle side surface of the lock near the first end defines a knuckle locking face and a coupler side surface of the lock that is opposite to the knuckle side surface defines a coupler locking face, the casting assembly comprises:

drag and cope portions of a first mold that defines exterior surfaces of the lock, wherein the first mold comprises a first molding material;

a second mold formed of a second molding material, the second mold defines a cavity with an interior surface that substantially complements an exterior surface of the first mold

a down sprue formed in the second mold;

a gating system formed in the second mold that is in fluid communication with the down sprue;

an in-gate formed in the second mold that is in fluid communication with the gating system and the first mold.

26. The casting assembly according to claim 25, wherein the first mold is a shell mold.

27. The casting assembly according to claim 25, wherein a parting line of the first mold that separates the cope portion from the drag portion follows a non-linear contour of the lock.

28. The casting assembly according to claim 25, wherein the first molding material is a mixture of silica sand covered and a thermosetting phenolic resin.

29. The casting assembly according to claim 27, wherein the second molding material is an air-set material.

30. The casting assembly according to claim 25, wherein the first molding material and the second molding material are a same material.

31. The casting assembly according to claim 25, wherein at least one of the cope portion and the drag portion of the first mold defines a protrusion that forms the slot.

32. The casting assembly according to claim 25, wherein the interior of the drag portion of the second mold is configured to receive at least two shell molds and to distribute the molten material to each of the at least two shell molds.

33. The casting assembly according to claim 25, wherein the in-gate to the lock that is formed during casting is configured to be broken off.

34. The casting assembly according to claim 33, wherein a diameter of the in-gate is less than about 2 inches.

35. The method according to claim 33, wherein the in-gate to the lock is located on a top of the first end.

36. A method of manufacturing a lock of a railcar coupler, where the lock includes a rear guide portion at a first end, a leg portion in a middle section, and a slot at a second end, where a knuckle side surface of the lock near the first end defines a knuckle locking face and a coupler side surface of the lock that is opposite to the knuckle side surface defines a coupler locking face, the method comprising the steps of:

forming, in a second mold that comprises a second molding material, a cavity with an interior surface that substantially complements an exterior surface of the first mold; and

forming, in the second mold, a down sprue, a gating system in fluid communication with the down sprue, a riser in fluid communication with the gating system, and an in-gate in fluid communication with the gating system and the first mold.